There won't be a decrease in key prices, in a VERY long time. The problem is that its not a rise in key prices, but a drop in ref prices. Refined is diluted, based on how many people run idle accounts and just flat out how many people play the game. The more people who break down all their items, and then want to buy the hats they want instead of crafting a random hat, means that valve's method of taking currency out of the economy isn't working.

If no currency leaves the economy, then currency floods the market and the value of said currency drops. Unless valve finds some way to mass pull refined out of the market, keys will never drop in price.